戴克伊GD&T基础资料

FundamentalsofGD&T基础几何尺寸与公差概述BasedonASMEY14.5M-2009Editedby:MikeLong戴克伊公司参考资料编译：龙东飞ASMEY14.5M-2009CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级GOAL目标•Understandwhatanengineeringdrawingis.懂得什么是工程图纸•Understandwhygeometrictolerancingissuperiortocoordinatetolerance.懂得为什么几何公差优于坐标共差•Understandthemodifiersandsymbolsusedingeometrictolerancing.懂得几何公差修饰符和符号•Remember:Tolerancesshouldbeaslargeaspossibletokeepmanufacturingcostlow.记住:为了降低制造成本，公差应该越大越好。CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级ENGINEERINGDRAWINGS工程图纸•TheNeedforPreciseCommunications精确交流的需要Engineeringdrawingsareacommunicationstools.Engineeringdrawingsaffectmanypartsofanorganization.Theyhavemajorimpactoncosts.工程图纸是精确交流的工具，对机构许多部门和成本构成重大影响。•ConsequencesofPoorDrawings品质差图纸后果(Costinfourways:Money,Time,Material,Unhappycustomers)（4种成本：钱、时间、材料、不满意的客户）CostofaDrawingError图纸错误的成本Whendiscoveredbythe…DesignDept.设计Modelshop样件ProductionGroup生产Customer客户$1-10$100-500$2,000-100,000$50,000-$1,000,000Figure1-1CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级•TypesofTolerances公差的类型-Alimittolerance极限公差(12.0-12.5)-Aplus-minustolerance正负公差(12.250.25equalbilateraltolerance)-Aunilateraltolerance单项公差(12+0.50)-Anunequalbilateraltolerance双向不等公差(12.2+0.3-0.2)(Wherelimitorbilateraltolerancingisused,eachtolerancevalueshouldhavethesamenumberofdecimalplaces,usingzeroswherenecessary.)当使用极限或双向公差时，每个公差值小数点后应该有同样多位数，必要时用零)CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级•InterpretingDimensionalLimits解读尺寸极限Alldimensionallimitsareabsolute.Adimensionisconsideredtobefollowedbyzerosafterthelastspecifieddigit.所有极限尺寸都是绝对精确值，其最后一个数字后面都是零。26.02means26.020…026means26.0…016.54means16.540…016.5means16.50…0Forthisdimension26.0-26.2Apartmeasuring26.201wouldberejectedAnd25.999wouldberejected•GD&TintheUnitedStatesGD&T在美国ASME(AmericanSocietyofMechanicalEngineers)Y14.5(thestandardnumber)M(Metric)-2009(theyearthestandardwasapproved)isarevisionofASMEY14.5M-1994ASME（美国机械工程师协会）Y14.5（标准编号）M（公制）-2009（标准批准年份）是ASMEY14.5M-1994标准的升级版•TheISOandASMEY14.5Mdimensioningstandardsarecurrently80-90%common.ISO标准和ASMEY14.5M标准目前有80-90%相同。CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级•ASMEandISODimensioningStandardComparisonASME和ISO标准比较ISOASMEY14.5Approachtodimensioning编写方式Theoreticaldefinition理论性强Functionofproduct功能性强Levelofexplanation解释方式Fewwords/manyfigures文字少/图表多Thoroughexplanation解释透彻Costofstandards标准售价Over$1000Lessthan$200Numberofstandards标准数目10-151CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级FUNDAMENTALDIMENSIONINGRULES(Rule#6)(ASMEY14.5M-1994)基本尺寸规则（6号规则）(ASMEY14.5M-1994)1.Eachdimensionshallhaveatolerance,exceptthosedimensionsspecificallyidentifiedasreference,maximum,minimum,orstock(commercialstock)size.每个尺寸都应该有一个公差，但是，参考、最大/最小或型钢尺寸除外。2.Dimensioningandtolerancingshallbecompletesothereisfulldefinitionofeachpartfeature.尺寸和公差应完整，才能完全定义零件形体。3.Dimensionsshallbeselectedandarrangedtosuitthefunctionandmatingrelationshipofapartandshallnotbesubjecttomorethanoneinterpretation.尺寸选择和布置，要适合零件功能和装配关系，而且只能有一种解释。4.Thedrawingshoulddefineapartwithoutspecifyingmanufacturingmethods.图纸只定义零件，不要注明生产工艺。5.A900angleapplieswherecenterlinesandlinesdepictingfeaturesareshownonadrawingatrightangles,andnodimensionisshown.900角在图纸上不标出。CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级6.Impliedbasic900angles-A900basicangleapplieswherecenterlinesoffeaturesinapattern(orsurfacesshownatrightanglesonadrawing)arelocatedanddefinedbybasicdimensionsandnoangleisspecified.基本900角在图纸上不标出。Impliedbasiczerodimension–WhereacenterlineorcenterplaneofaFOSisshowninlinewithadatumaxisorcenterplane,thedistancebetweenthecenterlinesorcenterplanesisanimpliedbasiczero.基本0尺寸在图纸上不标出。7.Unlessotherwisespecified,alldimensionsareapplicableat200C.零件常温200C8.Alldimensionsandtolerancesapplyinthefree-statecondition.零件自由状态。9.Unlessotherwisespecified,allgeometrictolerancesapplytothefulldepth,length,andwidthofthefeature.除非另有说明，几何公差应用全部形体长、宽、高。10.Dimensionsandtolerancesapplyonlyatthedrawinglevelwheretheyarespecified.Adimensionspecifiedonadetaildrawingisnotmandatoryforthatfeatureontheassemblydrawing.尺寸公差应用于它标明的层级，装配图尺寸公差不能强制该层级尺寸公差。CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级THECOORDINATETOLERANCILNGSYSTEM坐标公差•Definition定义Coordinatetolerancingisadimensioningsystemwhereapartfeatureislocated(ordefined)bymeansofrectangulardimensionswithgiventolerances.用直角坐标系尺寸和公差定义零件位置或用尺寸和公差定义形体。SHORTCOMINGSOFCOORDINATETOLERANCING坐标公差缺点•SquareToleranceZones方形公差带(Figure1-2)•Fixed-SizeToleranceZones固定尺寸公差带(Figure1-2)Figure1-2Cylindricalvs.Squaretolerancezone圆柱对比方形公差带Squaretolerancezonethatresultsfromcoordinatetolerances坐标公差方形公差带Cylindricaltolerancezonethatresultsfromgeometrictolerancing几何公差圆柱形公差带(57%additionaltolerance增加公差带57%)CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级•AmbiguousinstructionsforInspection检测指导不明确(Figure1-3)ShouldtheholelocationbemeasuredasshowninsetupAorB应该用A或B方法测孔的位置ABFigure1-3MethodofInspection检测方法SurfacePlate(Datumfeaturesimulator)SurfacePlate(Datumfeaturesimulator)CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级•Appropriateusesforcoordinatetolerancing正确使用坐标公差-Plus/minustolerancing